Need info on Congress playing cards (4 seasons, Norman Rockwell, in box)

Can anyone tell me what year these are from and the approximate value? The set belonged to my grandmother so I'm not interested in selling it, I'm only wondering the approx. value so I know how careful I should be in storing them. What is the best way to protect other than keeping out of sunlight?

Congress Playing cards
Box has faux marble top, black bottom. White satin on inside top lid with "Congress Playing Cards." Bottom inside is velour or velvet. Four decks represent the four seasons, designed with Norman Rockwell paintings. No missing cards, all perfect except for one Trump card with a very small indent on the edge. "Winter" deck is still wrapped in plastic.